Liquid Crystal Composition with Reactive Mesogen for VA Display
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Solution Overview
Problem
Liquid crystal displays, particularly Vertical Alignment (VA) type, face limitations in reducing cell gap to enhance response speed due to quality and process issues such as yield decrease and increased darkness from foreign substances, and existing methods struggle to improve voltage holding ratio and reduce residual images.
Innovation Solution
A liquid crystal composition incorporating a first compound and a reactive mesogen, with specific chemical formulations, is used to improve viscosity and rotational viscosity, along with an antioxidant to prevent oxidation and maintain stability, thereby enhancing voltage holding ratio and reducing line and surface residual images.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If cell gap is reduced to improve response speed, then response speed increases, but manufacturing quality deteriorates due to foreign substances causing yield decrease and darkness
Solution Approach 1:
The patent changes the chemical composition parameters of the liquid crystal material by incorporating reactive mesogen compounds (specifically cyclohexyl and phenyl compounds with fluorine or chlorine atoms) in controlled amounts (0.02-0.03 wt%). This compositional parameter change improves the liquid crystal's inherent properties including voltage holding ratio and response characteristics without requiring cell gap reduction, thereby avoiding the manufacturing quality issues associated with smaller cell gaps.
Solution Approach 2:
The patent creates a composite liquid crystal composition by combining multiple liquid crystal compounds including the first compound (Formula 1), reactive mesogen (Formula 2), and third compound (Formula 7). This composite approach synergistically improves multiple properties: the reactive mesogen enhances voltage holding ratio and response speed, while the overall composition maintains stability and prevents the formation of harmful byproducts, thus resolving the contradiction between response speed and manufacturing quality.
2Ease of manufacture
If conventional liquid crystal composition is used, then manufacturing is simple, but voltage holding ratio is insufficient and residual images occur
Solution Approach 1:
The patent modifies the chemical composition parameters by introducing specific reactive mesogen compounds (Formula 2) with controlled amounts (0.02-0.03 wt%). This parameter change specifically targets and improves voltage holding ratio and response characteristics. The addition of antioxidant compounds (Formula 7) at 0.001-0.05 wt% prevents oxidation-related degradation, thereby eliminating residual images while maintaining manufacturing simplicity through a straightforward compositional formulation approach.
3Adaptability or versatility
If liquid crystal material with negative dielectric anisotropy is used for VA type displays, then viewing angle and response characteristics improve, but viscosity and rotational viscosity increase
Solution Approach 1:
The patent optimizes the molecular structure parameters of the liquid crystal compounds, specifically using cyclohexyl and phenyl groups with controlled alkyl chain lengths (m=0-4, n=1-2) and substituent types (fluorine, chlorine, alkyl, alkoxy groups). This parameter optimization achieves negative dielectric anisotropy for VA type display compatibility while controlling viscosity. The reactive mesogen addition further modifies the liquid crystal properties to improve response speed without excessive viscosity increase.
Solution Approach 2:
The patent formulates a composite liquid crystal composition combining multiple compounds with different molecular characteristics. The first compound (Formula 1) provides base liquid crystal properties, the reactive mesogen (Formula 2) enhances response and voltage holding, and the third compound (Formula 7) acts as antioxidant. This composite approach balances negative dielectric anisotropy for VA display performance with controlled viscosity and rotational viscosity through synergistic interactions among components.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The composition improves response speed, voltage holding ratio, and reduces residual images, maintaining phase stability and image quality while preventing polar byproduct formation and oxidation-related issues.
Implementation Method 1
a liquid crystal composition including reactive mesogen ("RM")
Implementation Method 2
an antioxidant to prevent oxidation and maintain stability, thereby enhancing voltage holding ratio and reducing line and surface residual images
Data Source
AI summary
A liquid crystal composition includes a first compound expressed by following Chemical Formula 1 and about 0.001 wt % to about 0.05 wt % of a second compound expressed by following Chemical Formula 2,where A and B are a cyclo-hexyl group or a phenyl group, m is 0 to 4, n is 1 to 2, X is an alkyl group or an alkoxy group, and Y is one or two fluorine (F) or chlorine (Cl) atoms, andwhere n is 0 to 2, I is 0 to 1, Z is a halogen group, an alkyl group, or an alkoxy group, and A and A′ are methyl groups that do not independently exist.